In a proposed rotary hammer (see German Patent Application P32 05 141), the hub body of a wobble plate drive is provided non-rotatably on a cylindrical portion of an intermediate shaft, the longitudinal axis of this cylindrical portion being inclined in relation to the longitudinal axis of the intermediate shaft. In the inner surface of the hub body recesses are provided, which are engaged with projections on the cylindrical portion of the intermediate shaft, resulting in a positive engagement by which a non-rotatable coupling between the intermediate shaft and the hub body is achieved. To vary the hammering stroke of the pneumatic hammering mechanism, the hub body can be physically disengaged from the projections on the cylindrical portion of the intermediate shaft, so that the cylindrical portion can be turned and re-engaged with the projections, resulting in a different position of the hub body on the cylindrical portion of the intermediate shaft. In this way, the inclination of the hub body of the wobble plate drive is altered in the common plane of the longitudinal axis of the intermediate shaft and of the wobble finger provided on the outer race of the wobble plate drive; thus, the stroke of the wobble finger, and thereby also the hammering stroke of the pneumatic hammering mechanism, are altered. This rotary hammer therefore enables the user to manually pre-select and set, before use, a larger or smaller hammering stroke, and therefore apply more or less hammering energy when using the rotary hammer.
Another rotary hammer has been proposed (see German Patent application P 29 17 475), in which the user can alter the hammering stroke of the pneumatic hammering mechanism by altering in use the inclination of a drive plate, mounted so it can swivel on a rotating intermediate shaft, whereby different hammering strokes can be produced.